Railway track circuit apparatus



July 26, 1938. B. E. O'HAGAN 2,124,529

- RAILWAY TRACK CIRCUIT'APPARATUS Filed oct. 30. 1957 Fig? 1.

Signal 28 Control 2 INVENTOR v j Benxardz O'Iizgan I HIS ATTORNEYPatented July 26, 1938 UNITED STATES PATENT owner.

The Union Switch & Signal Company, Swissvale, Pa., a corporation ofPennsylvania Application October 30,

' 15 Claims.

form of the apparatus of Fig. 1, also embodying my invention. A

Similar reference characters refer to similar parts in each of the twoviews.

Referring to Fig. 1 of the drawing, the reference characters I and 2designate the track rails of a section of railway track defined byinsulated'rail joints 3 at each end of the section. Connected across therails at one end of the track section is asource of current 4, hereshown as abattery, which supplies current to the track circuit over acurrent limiting resistor 5.

The reference character'R. designates a track relay comprising threeparallel cores 6, I, and 8,.

two of which, 6 and 8, are connected at their upper ends by abackstrap9." The remaining core 1 is spacedfrom the backstrap by an air gap Ill.The cores 6- and 8 are provided with operating windings I I and I2,respectively, which receive energy from the rails of the section overcircuits which will be traced in detail herein-- after. Accordingly, twomagneticcircuits are provided,-one of which includes core 6 and theother of which includes core 8, with the core 1 common to bothmagneticcircuits. The windings II and I2 are so disposed that the fluxesdue to these windings aid one another in the common core I. Core 6 isequipped with a shortcircuited retarding winding I3, and core 8 isequipped with a similar winding l4, but the latter winding is normallyan open circuit and becomes short-circuited only when the secondaryrelay S is released.

A tractive armature I5 is pivotally supported at bearing I6 for swingingmovement toward and away from the cores 1 and 8, and a similar tractivearmature I1 is similarly supported for movement with respect to cores 6and I. The armatures I5 and H are biased by gravity to an open positionaway from the respective cores and carry contactfingers l8 and I9 which,in the closed armature position shown in the draw- 1937, Serial No.171,928

ing, engage fixed contacts 20 and 2|, respectively.

The secondary relay S receives operating energy from a suitable sourceof current having the terminals BC, over the front contact I9- 2! ofrelay R. Relay S controls, over its back contact 2223, theshort-circuiting of winding M, and over its back contacts 24-25 and26-21, the closing of the pick-up circuit for relay R. Relay S ispreferably designed to have a slightly 1 retarded pick-up so that amomentary closure of contact l9 2l will not cau'se relay S to pick up,thus avoiding undesired signal flashes due to opening of' contact 28-29and closing of co'ntact 28-40,- which might otherwise result duri-ng amomentary loss of shunt.

Having described the various elements of Fig. 1 comprising the apparatusembodying my 'invention, I shall now describe the operation of thisapparatus- When the track section is unoccupied, the apparatus will bein the condition in which it is illustrated in Fig. 1 of the drawing.That is, relay R will be maintained energized over a holding circuitwhich may be tracedfrom thelefthand terminal of battery 4', limitingresistor 5, rail 2, winding II, wire-3|, resistor 32, upper portion'ofwinding I2, wire 33, front contact I'8-20, wires 34' and 35, and rail I,to the righthand terminal of the battery. The secondary relay S 'will bemaintained energized over front contact I92l of relay R, and so theappropriate signal circuit will be closed at front c'orltact 28 .38 ofthis relay. The pick-up circuit for relay R and the circuit for theretarding 35 winding I4 will both be open. The. purpose served byresistor 32 included in the holding circuit is to compensate eitherwholly or partly, as desired, for the resistance of those turns ofWind'- i-ng I2 which are excluded when the holding .circuit iseffective.

, When a train enters the section, the shunt formed by the wheels andaxles of the train will considerably reduce the current which traverseswinding II and the upper portion of winding I2iin the holding circuit.Accordingly, the flux in cores 6 and 8 will rapidly decrease, but due tothe presence of the short-circuited winding l3, the decrease of flux inthe magnetic circuit of cores 6 and I will be less rapid than in the 50corresponding magnetic circuit of cores 8 and I. There will, therefore,be present a magnetomotive force due to the magnetic circuit of cores 6and I whichwill oppose the flux in the magnetic circuit of cores 8 andI, which magnetomotive V net to a lower value than would occur merelycombination.

by virtue of the decrease in current of winding l2. magnet will releaseat a higher value of train shunt resistance than it would without theopposing effect of theflux in the right-hand magnet, and will thusprovide a higher degree of shunting sensitivityv than is provided in theusual and well-known primary-secondary relay It will be apparent thatWinding l3 has a discriminating effect between a slow decrease inenergization'of relay R such as occurs when the ballast resistancedecreases, and a relatively rapid decrease, in energization such asoccurs when a train enters the section. Accordingly, winding I3 iseffective in improving the shunting sensitivity of relay R:by raisingthe release value of armature I5 and inaccelerating the release of thisarmature only under the train shunt condition, this winding beingnormally inactive'during changes'in ballast resistance.

As soon as armature l5 releases, front contact l8-2l) will open and willinterrupt the circuit for both windings II and I2, whereupon armature llof the right-hand magnet will quickly release. The release of armatureI! will open the circuit a for relay S at contact the retarding winding14 aswell as the pick-up circuitfor relay R. The'pick-up circuit may betraced from rail 2, winding ii, wire 35, back contact 26-21 of relay S,wire 31, full winding l2,

wires 33 and 38, back contact 2 4251of relay 8;. and Wire 35, to rail l.

Preferably, the windings ii and I2 will each have the ,same number ofturns so that the right-hand and left-hand magnets may be similarly orinterchangeably designed. If desired, the windings 7H" and I2 may bereplaced by a single winding positionedon the common core 7 andsupplying the necessary fiuX to the two magnetic circuits. By suitablytapping the single winding, aholding circuit of a decreased number ofturns, similar to'that for the pair of windings II and I2 may beobtained. w e

The reason for equipping core 8 with a retarding winding [4 which issimilar to winding IS on core 6 is to provide similar conditions duringpickup for both magnets so that at this time both cores 6 and 8 willhavethe same number of short-circuited turns as well as the same numberof operating turns. Accordingly, when a train leaves the section, botharmatures i5 and I1 will become attracted at about the same time,although this'condition is not essential from the standpoint ofoperativeness. That is, winding I 4. may be dispensed with, if desired,provided the apparatus is so proportioned that a prior pickup of onearmature IE or I! will not prevent the other armature from picking up.

Under certain conditions; as Will'be explained more fully in connectionwithFig. 2, it may be advantageous to eliminate winding [4 in order thatarmature l5 will be first to pick up, thus delaying the'pickupofarmature I1 and introducing a corresponding delay in the pickup ofrelay S.

When the section becomes unoccupied, relay R will pick up and theclosing of contact I820 will reestablish the holding circuit previouslycause relay S to pick upwhich will, in turn, open the pick-up circuitfor relay. R and the circuit for winding I4, thereby restoring thesensitive As a result, armature [5 of the left-hand 3960 alone. l92l,releasing this relay and closing 'vantage of this arrangement is that aquicker release of relay S will be obtained by virtue of w the fact thatarmature I5 is first to .releas'e,-so that the signals will respond morequickly to V the entry'of a train into the section.

In thisfigure, the circuit for relay S mayor may not be carried over thecontact I9-2I of the'right-hand magnet, as desired. If relay S is astandard relay which does not have slow pickup characteristics and ifthe retarding coil 14 is not used, then it may be desirable to includeboth contacts 39-4!!! and l92l in the circuit. for relay S, so as totime-delay the pickup of the relay. In this manner, an operationequivalent to that of Fig. 1 with an inherently slow. pick-up relay Smay be obtained. By usinga 1 a slow pick-up relay, however, the contact9-2l may be completely eliminated, the pick-upcircuit for relay S beingA further difference between Figs. 1 and 2 is that in the latter figurethe wiring for the pickup and holding circuits is slightly rearranged soas to eliminate the extracontact 2425 of relay S. In all other respects,however, the pickup and holding circuits for relay R are the same as inFig. 1, and will be obvious from the drawing without furtherexplanation.

It will be apparent that" the improvement in shunting sensitivity ofrelay R which I obtain then carried over contact is .due to two factors,namely,'a higher release.

of armature l5 by virtue of the opposing magnetomotive force resultingfrom the unbalance between the right-hand and left-hand magnets at thetime the track is shunted, and a higher release of this armature due tothe decreased ampere-turn magnetization of the relay when the holdingcircuit is effective. However, in-

order to realize the advantages of myinvention it is not essential thatthe normal energizing circuit for relay R include a resistor and excludea portion of the operating winding, or thatthe holding ampere-turns bedecreased, so that the secondary relay S may be dispensed with entirely,if desired. That is, the full turns of both windings I l and I2 may beused not only at pickup, but also during the normal holding operation ofthe relay. One manner in which the effect of fewer holdingampere-turnsmay be obtained hand magnets will also be unequal, the fluxin the right-hand magnet being the greater of the two, so that armatureI5 will have its release point substantially raised. By properlyadjusting this flux diiference, armature l5 may be brought as close tothe release point whena given shunt is applied to the track, as though aholding circuit of decreased ampere-turns were used.

Although I have herein shown and described only two forms-ofrailwaytrack circuit apparatus embodying my invention, it is understoodthat various changes and modifications may be made therein within thescope of the appended claims without departing from thespiri't and scopeof my invention. 1 I

Having thus described my invention, what I claim is:

1. In combination with a section of railway track and a source ofcurrent connected across the'rails of said section, a primary relayhaving a first and a second magnetic circuit each including a commonmagnetic path, means associated with said first magnetic circuit forretarding the flux decay therein when said track section becomes shuntedto thereby accelerate the flux decay in said second magnetic circuit, asecondary relay, an energizing circuit for said secondary relayincluding a contact of said primary relay, a

pick-up circuit for said primary relay connected. across the rails ofsaid section and including a contact of said secondary relay as well asthe full operating winding of said primary relay, and a holding circuitfor said primary relay controlled by a contact governed by said secondmagnetic circuit and including only a portion of the operating windingof said'primary relay.

2. In combination with a section of railway track and a source ofcurrent connected across the rails of said section, a primary relayhaving a first and a second magnetic circuit each including a commonmagnetic path, means associated with said first magnetic circuit forretarding the flux decay therein when said track section becomes shuntedto thereby accelerate the flux decay in said second magnetic circuit, asecondary relay, an energizing circuit for said secondary relayincluding a contact of said primary relay, a pick-up circuit for saidprimary relay connected across the rails of said section and including acontact of said secondary relay as well as the full operating winding ofsaid primary relay, a resistor, and a holding circuit for said primaryrelay controlled by a contact governed by said second magnetic ,3circuit and'including only a portion of the operating winding of saidprimary relay and said resistor.

3. A track relay for improving the shunting sensitivity of a trackcircuit comprising, in combination, two magnetic circuits for said trackrelay each including a common magnetic path and each adapted to beenergized from the track, a control armature for said track relayassociated with one of said magnetic circuits, and means associated withthe other of said magnetic circuits and discriminating between arelatively slow decrease in energization of the track relay such asoccurs due to a decrease in ballast resistance and a relatively rapiddecrease in energization of the track relay such as occurs due to atrain shunt for accelerating the release of said armature when saidtrack relay becomes shunted.

4. A track relay for improving the shunting sensitivity of a trackcircuit comprising, in combination, two magnetic circuits for said trackrelay each including a common magnetic path and each adapted to beenergized from the track, a control armature for said track relayassociated with one of said magnetic circuits, and means associated withthe other of said magnetic circuits for retarding the fiux decay thereinwhen the track becomes shunted to thereby accelerate the flux decay insaid one magnetic circuit and so to accelerate the release of saidarmature.

5. A track relay for improving the shunting sensitivity of a trackcircuit comprising, in com bination, two magnetic circuits for saidtrack relay each including a common magnetic path and each adapted to beenergized from the track, a control armature for said track relayassociated with one of said magnetic. circuits, a shortcircuited windingassociated with the other of said magnetic circuits for retarding theflux'decay therein when the track becomes shunted to thereby acceleratethe fiux decay in said one magnetic circuit and so to accelerate therelease of said armature.

6. A track relay for improving the shunting sensitivity of a trackcircuit comprising in combination, a first and a secondmagnetic circuitfor said track relay each including a common magnetic path and eachadapted to be energized from the track, a first and second armatureassociated respectively with said first and second magnetic when thetrack becomes shunted'to accelerate the flux decayin said secondmagnetic circuit and so to release said secondarmature before said firstarmaturereleases, and signaling apparatus controlled by a said twoarmatures.

'7. In combination with a section of railway track and a source ofcurrent connected across ciated with the other of said magneticcircuits. v

. 8. In combination with a section of railway track and asource ofcurrent connected across the rails of said section, a track relay havingtwo' magnetic circuits each including a common magnetic path, a circuitincluding the rails of said section for energizing said two magnticcircuits, an armature associated with one of said magnetic circuits, andmeans associated with the other of said magnetic circuits effective whensaid track section becomes shunted by a train for accelerating therelease of said armature.

9. In combination with a section of railway track and a source ofcurrent connected across the rails of said section, a track relay havingtwo magnetic circuits each including a common magnetic path, a circuitincluding the rails of said section for energizing said two magneticcircuits, an armature associated with one of said magnetic circuits, anda short-circuited winding associated with the other of said magneticcircuits effective when said track section becomes shunted by a trainfor retarding the flux decay in said other magnetic circuit so as toaccelerate the flux decay in said one magnetic circuit and expeditenetic path, a circuit including the rails of said trolled by saidarmature for improving the. shunting sensitivity of said track relay.

11. In combination with a section of railway track and a source ofcurrent connected across therails of said section, a track relayhavingtwo magnetic circuits each including a common magsectionforenergizing said two magnetic circuits, an armature associated witheach of said magnetic circuits, means associated with one of saidmagnetic circuits effectivewhen the track section becomes shunted by atrain for acceleratingthe release of the armature associated ,Withtheother of said magnetic circuits, and means controlled by both saidarmatures for improving the shunting sensitivity of said track relay.

12. In combination with a section of'railway track and a source ofcurrent connected across the rails of said section, a track relay havinga first and a second magnetic circuit each including a common magnetic.path, a circuit including the ;rails of said section for energizing saidfirst and said second magnetic'icircuits, afirst and a second armatureassociated respectively with said first and said second magneticcircuits, means associated with said'second magnetic circuit foraccelerating the release of said firstarmature upon shunting of saidtrack section, an auxiliary relay 7 controlled by said first armature,and means controlled by said auxiliary relay and effective when theshunt is removed from said track section for equalizing the pick-up timefor said first and second armatures. v I g 13. In ccmbinationwith asection of railway track and a source of current connected across therails of said section, a track relay having two magnetic circuits eachincluding a common mag- I relay.

netic path, means receiving energy from the rails r of said section-forsetting up, aiding fluxes in said two magnetic-circuits, an armatureassociated Withone of said magnetic circuits, and

means associated with the other of said magnetic.

circuits effective upon a rapid decrease of the energy received fromsaid rails when, a trainenters said section for aiding the releaseoflsaid armature. t i

14. A track relay for railway signaling track circuits comprising, incombination, twomagnetic circuits for'said trackrelay eachincluding acommon magnetic path, means for setting up aiding fluxes in said twomagnetic circuits,'and means associated with one of saidmagneticfcircuits effective upon a relatively rapid decrease of twomagnetic circuits, an armature associated with one of' said vmagneticcircuits, and means associated 'withthe other of 'said magnetic cir-.cuits and discriminating between a rapid decrease in the energy receivedfrom said rails such as occurs when a trainenters the section and a slowdecrease in saidenergy due to a decrease in bal last resistance formodifying the release value of said armature.

BERNARD E. OHAGAN.

